Forensic videography means that images are taken under controlled conditions that are substancially similar to those present at the time of the accident. High resolution digital cameras have the shutter speed, ISO, focal length, film back, aperture and altitude recorded. Equipment is calibrated such that it can be authenticated in the court room. The US Naval Observatory is also consulted to account for the sun's azimuth and altitude. Aerial images are rectified to ground surveys to accurately show lines of sight and obstruction areas.